Catalyst coated yarn handling roll

ABSTRACT

A surface for contacting a moving finish coated textile yarn at elevated yarn treatment temperatures in the presence of oxygen. The surface is characterized by irregular, rounded nodules which bears within its interstices finely divided catalyst particles that will catalyze oxidation of finish deposits that form on the surface at the yarn treatment temperature. The time between periodic cleaning cycles is greatly lengthened with attendant savings in labor and loss of production.

United States Patent 1191 Fernandes Sept. 2, 1975 [54] CATALYST COATED YARN HANDLING 3,080,134 3/1963 England 117/46 FS ROLL 3,266,477 8/1966 Stiles 254/477 3,414,427 12/1968 Lev 1 117/50 Inventor: Harold Fernandes, Newark, e 3,470,019 9/1969 Stee 1e..... 117/160 R 3,486,928 12/1969 Rhoda 117/71 R [73] Assgnee' 12 Nemours 3,676,188 7 1972 Silverman 161/213 "ma De 3,787,229 1/1974 Rudness 161/162 [22] Filed: June 20, 1974 [21] Appl. No.: 481,345 Primary Examiner-George F. Lesmes Related U s 7 Application Data Assistant Examiner-Ellis P. Robinson [62] Division of Ser. No. 266,000, June 26, 1972, Pat. No.

[57] ABSTRACT 52 US. Cl. 29 132; 29 121 R; 68 6; l R, 1 A Surface for Contacting a moving finish Coated textlle 2; g 428/457, 428/472 yarn at elevated yarn treatment temperatures in the [51] Int. C12 B213 5 B65H 57/00 presence of oxygen. The surface is characterized by [58] Field of 61/164 182 213 irregular, rounded nodules which bears within its in- 161/225, 29/ 132 19 242/157 terstices finely divided catalyst particles that will cata- 68/6 7/62 M {19.6 130 lyze oxidation of finish deposits that form on the sur- R face at the yarn treatment temperature. The time be- 1 tween periodic cleaning cycles is greatly lengthened [56] References Cited with attendant savings in labor and loss of production.

UNITED STATES PATENTS 2 Claims No Drawings 2,947,114 8/1960 Hill 161/225 CATALYST COATED YARN HANDLING ROLL CROSS REFERENCE TO RELATED APPLICATION This application is directed to material divided from my copending application Ser. No. 266,000 now U.S. Pat. No. 3,849,177 June 26, 1972.

BACKGROUND OF THE INVENTION This invention is related to the field of hot processing textile materials. More particularly, it relates to an improvement in means for treating textiles which have an organic finish on them, in which the textiles are in contact with hot metal surfaces.

There are many processes in which textiles are brought in contact with hot metal surfaces. Fabrics are conventionally heat set while passing over rolls in an oven. Tire cord is conventionally dipped and hot stretched in an oven. Warp yarn is normally coated with a size which is then heated to dry it. In the course of manufacture, synthetic filaments are often drawn or relaxed while in contact with heated metal surfaces, or while in an oven. In most of these processes, the filaments of the textile have a coating of organic material such as tire cord adhesive, size or yarn lubricating finish which may be rubbed off onto the metal surface with which they come in contact. Whether the metal surface is itself a source of heat, as is a conventional hot plate or hot tube such as are often placed in the draw zone, or whether the surface be yarn carrying rollers driven by external motors and housed in an insulated chest supplied with recirculating hot air, these deposits of organic material tend to form insoluble varnish on the roll surface. As these deposits accumulate, they cause yarn breakage. Consequently, a cleaning routine must be established, with attendant labor costs and interruption of production.

The prior art has recognized this problem and has tried to solve it by mechanical methods. Au in U.S. Pat. No. 3,068,530 passes yarn in helical wraps around a heated pipe. While in use, the pipe is slowly rotated so that such deposits that form are worn away by the running yarn. Marlborough et al. in U.S. Pat. No. 3,483,593 solve the same problem in a similar way by traversing the yarn to and fro in its path across a hot plate.

Although these cxpedients have provided some im provement when using stationary metal surfaces, they wont work when the yarn and metal surface move at the same speed as the rollers do which are needed in hot stretching ovens for tire cord or in hot chests where yarn is drawn, annealed or relaxed, for example, in the hot chest shown by A. N. Good in U.S. Pat. No. 3,31 1,691.

DEFINITION OF THE INVENTION The improvement of this invention is obtained in a process for heat treating a moving filamentary structure having a coating of a textile finish containing oxidizable organic components, wherein the structure is contacted with a surface at elevated temperatures within the range of about 100C. up to the melting point of the structure in the presence of oxygen. The improvement is obtained by using a surface characterized by irregular, rounded surface nodules, which bears within its interstices a catalytic amount of finelydivided platinum, palladium or mixtures thereof, whereby any finish components transferred to the said surface are oxidized to volatile by-products and harmless carbonaceous residues at the filament treatment temperature.

The surfaces which are to be impregnated with the catalyst must be clean and free from grease; a solution of soluble salt of the catalyst and a reducing agent is applied to a warm surface (e.g., a draw roll), the roll is heated to dry and reduce the catalyst to finely-divided platinum and/or palladium particles; the coating step may be repeated to provide a coating having about 0.03 to about 0.5 gm. of catalyst per sq. ft. of yarn contacting surface.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The preferred surface to which the catalyst is applied is the oxide-coated surface invented by England & Spellman in U.S. Pat. No. 3,080,134 which provides a low friction, abrasion-resistant surface by flame coating a metal yarncontacting surface of a yarn handling apparatus with a refractory oxide to produce a ceramic coating thereon. For reasons of mechanical strength or adequate heat transfer, it is frequently necessary to provide apparatus consisting primarily of metal. The ceramic coating is then lightly polished with abrasive, such as fine emery cloth, to produce a nodular surface having a surface roughness of 70 to 250 root mean square (rms) microinches, as measured with a conventional stylus-type measuring instrument reading directly in rms microinches, the surface being free from sharp peaks. The preferred refractory oxides used to provide this coating are Cr. ,O and A1 0 The oxide coating is especially desirable for use in combination with the platinum and/or palladium catalyst because these oxidation catalysts are conventionally used when deposited on a refractory oxide. Moreover, the roughness of the surface permits deposition of catalyst in the interstices, between the nodules, so that is is not abraded away by the running yarn.

It is surprising that the oxidation catalyst is effective in eliminating the organic residues at temperatures below the melting point of synthetic fibers. Conventionally, such catalysts are used at temperatures of over 400C, well above the melting point of all melt-spun fibers. In addition to platinum and palladium, other metals known to catalyze decomposition of organic materials at moderate temperatures may be employed, singly or, in combination. Typical metals are rhodium and ruthenium; the use of osmium and iridium will gencrally be uneconomical.

Any water soluble platinum or palladium salt can be used to prepare the treating solution for application to the metal surface. The platinum salts should be free from foreign ions which are not removable by volatilization during the reduction treatment, or by washing subsequently. Nitrate and nitrite salts of platinum and palladium are especially useful; the chloroplatinates and similar halogen containing compounds may have a corrosive effect which is harmful to metal parts.

Water soluble reducing agents such as hydrazine hydrate, hydroxylamine and aldehydes such as formaldehyde are useful, although it is quite possible to apply a solution of platinum salt to the metal surface, dry and reduce in an atmosphere of hydrogen.

Preparatory to applying the catalyst, the metal surface must be clean and free from oil or finish deposits. If newly coated with alumina, the surface may have the catalyst applied directly. If the article has been used in yarn production. it should be cleaned to be sure that no oil or finish remains to prevent the treating solution from wetting the surface. A very thorough cleaning method is to boil the article, such as a roll, in synthetic detergent solution, followed by rinsing and heating in a furnace for /2 hr. at 450C. Ordinarily, such thorough cleaning is not required, especially when reactivation of catalyst is all that is required.

If organic material deposits are allowed to build up on heated spinning equipment such as draw rolls, the residue will ultimately become visible as a varnish-like deposit. This deposit reduces yarn quality to an intolerable level. By yarn quality" is meant threadline breaks, broken individual filaments and yarn wraps built up on the rolls. It has been found necessary to clean rolls in commercial use every 3 /2 days; otherwise, yarn quality deteriorates rapidly to an intolerable level after about 4 days. Yarn quality improves immediately after this step is taken. This procedure has now become unnecessary in view of the instant invention.

When catalyst coated rolls have been in commercial use for 6 months or a year, it may be desirable to remove them, reclean by procedures described above and if needed, reimpregnate them with catalyst.

As mentioned above, the catalyst coated hot metal surfaces of the instant invention are useful in any process in which a textile coated with an organic material is heated to elevated temperatures. This will include use in heat setting ovens, processes in which fabric is coated and the coating cured, calendaring rolls, hot stretching ovens for tire cords, to name but a few. The invention is obviously useful for fiber manufacture, when high temperature treatment is necessary to induce stretching, setting, shrinking or crimping. The invention is especially applicable to the production of melt-spun fibers, since the heat treatment is often necessary in their manufacture yet excessive temperatures must be avoided due to their melt sensitivity. Among this group are the polyamides (nylons), the polyesters such as the polymethylene terephthalates and the polyolefins such as polypropylene.

EXAMPLE 1 The melt-spinning and drawing process disclosed by A. N. Good in U.S. Pat. No. 3,311,691 is used in this example. In accord with the process therein disclosed, poly (hexamethylene adipamide) is melted, extruded through spinneret orifices to form a 210 filament yarn and the filaments are cooled and forwarded to feed rolls 2, 3 as shown in the drawing of the Good patent. Prior to contacting feed rolls 2, 3, a lubricating finish of the type described by Coats in U.S. Pat. No. 3,248,258 is applied to the threadline. This finish deposits about 1.5% (based on wt. of yarn) oil and other nonvolatile organic material on the running threadline.

After feed rolls 2, 3, the filaments are snubbed and drawn over pin 4 in the first drawing stage, pulled by draw rolls 5, 6. The filaments then pass in helical wraps around hot pipe 7, where second-stage drawing occurs. The filaments then pass into hot chest 10, where they are annealed at constant length while passing in wraps around driven rolls 12, 13. Rolls 12 and 13 are 6% inches in diameter and have a face length (in the axial direction), on which the yarn runs, of 9 /4 inches. They have been given a coating of Cr O in accord with the teachings of England et al. in U.S. Pat. No. 3,080,134 which provides them with a hard ceramic coating characterized by rounded surfaces nodules having a surface roughness in the range of to 250 rms mieroinches. Some of the rolls used in the test have not been used subsequent to applying the ceramic coating; others, which have been used, are furnace-cleaned by the procedure described above. Prior to the test, the rolls are treated as follows.

Treating solution A is prepared by dissolving 16.8 gm. platinum diamminedinitrite [Pt(NH ,(NO in 500 ml. of dilute ammonium hydroxide (1 part of 28% NH,OH reagent solution to two parts water, by vol.), at a temperature of about 70C. The platinum compound is converted to the tetrammine complex, NH3)-I(NO2)2 Treating solution B is prepared by mixing 22.5 gm. hydrazine hydrate, H. ,N.NH- .H O with 450 ml. water.

Equal volumes of solutions A and B are mixed and about 20 ml. of the mixture is applied to the yarn contacting surface of each roll while in the temperature range of 70 to C. The coating is carefully applied to the entire surface, coating from top to bottom. The rolls are then heated in an oven for 1 hr. at 200C. After cooling to 7080C., a second application of about 20 ml. of the catalyst solution is applied, followed by oven heating. Each roll has a deposit of about 0.4 gm. platinum. The rolls may be stored for subsequent use. For the present test, they are installed in a hot chest similar to 10 (rolls 12, 13).

For the purpose of this test, the hot chest is operated at a temperature of 210C. Yarn residence time in the hot chest is about 0.3 sec. Yarn of excellent quality is produced for a period of 30 days, without any roll cleaning. The test is discontinued in order to return to conventional production procedures.

In contrast, conventionally produced yarn from an adjacent spinning position, (on which no catalyst was used), required that the hot chest rolls be cleaned twice a week to maintain good yarn quality.

EXAMPLE I] When the test of Example I is repeated on a full spinning machine basis, starting with rolls newly coated with Cr- O producing 1260 denier, 210 filament yarn and using a hot chest temperature of 210C., good quality yarn is produced for 5 months, without intermediate roll cleaning and essentially without broken filaments due to finish deposits on the rolls. In contrast, normal production of yarn without the catalyst, required roll cleaning twice a week.

What is claimed is:

1. A yarn handling roll having a yarn contacting surface characterized by irregular, rounded nodules hav ing a surface roughness of from about 70 to about 250 root means square microinches, there being interstices between the nodules, said interstices bearing catalytic particles selected from the group consisting of platinum and palladium, said particles having a surface density of from about 0.03 to about 0.5 gram per square foot.

2. The yarn handling roll as defined in claim 1, said yarn contacting surface being a ceramic coating prepared from a refractory oxide selected from the group consisting of chromium and aluminum oxides. 

1. A YARN HANDLING ROLL HAVING A YARN CONTACTING SURFACE CHARACTERIZED BY IRREGULAR, ROUNDED NODULES HAVING A SURFACE ROUGHNESS OF FROM ABOUT 70 TO ABOUT 250 ROOT MEANS SQUARE MICROINCHES, THERE BEING INTERSTICES BETWEEN THE NODULES, SAID INTERSTICES BEARING CATALYTIC PARTICLES SELECTED FROM THE GROUP CONSISTING OF PLATINUM AND PALLADIUM, SAID PARTICLES HAVING A SURFACE DENSITY OF FROM ABOUT 0.03 TO ABOUT 0.5 GRAM PER SQUARE FOOT.
 2. The yarn handling roll as defined in claim 1, said yarn contacting surface being a ceramic coating prepared from a refractory oxide selected from the group consisting of chromium and aluminum oxides. 